1. Field of the Invention
The present invention relates to a divided polygon drawing method and device therefor, for use in a graphic drawing device applied to the field of computer graphics and, more specifically, to a method of divided polygon drawing capable of high-speed generation of vertex information when dividing a polygon, and to a device therefor.
2. Description of the Related Art
Devices and methods for dividing a convex polygon into triangles and drawing the convex polygon on a high-speed triangle drawing device have been known in the past.
A prior art graphic drawing device generally consists of a convex polygon dividing device which divides the convex polygon into triangles, and a triangle drawing device which has a plurality of triangle drawing means, the processing of the plurality of triangle drawing means being performed simultaneously, with drawing being done on a display device.
In the above-noted graphic drawing device, the following problems arise when dividing a convex polygon into triangles.
Of the vertex information of the convex polygon, there are cases in which, by dividing a convex polygon, the same given vertex will have different vertex information in different adjacent triangles. One such type of information is information for each vertex of a convex polygon which controls the respective edges from a vertex to the next vertices, for example, the information which controls the visibility of the external perimeter. In the discussion which follows, the term "vertex data" will be used for vertex information which does not change due to division, the term "edge data" will be used for other vertex information, the term "edge data" will be used for edge data which does not change due to the division, and the term "divided edge data" (indicating that the line is not visible) will be used for edge data which changes because of the division.
In the past, when using "vertex data" to draw the separated triangles, after performing filling in, etc., of the areas inside each of the triangles using the coordinates of each of the vertices, the above-noted "vertex data" and "edge data" were used to draw the surrounding outline. The reason for this was that there were cases when the division would cause the "edge data" which belonged to a vertex (vertex data) to become "divided edge data."
Therefore, with the prior art technology, there was a problem in that it was not possible to draw the surrounding outline until the drawing of all of the triangles was completed, the processing speed being established by the processing for the drawing of the triangles, which requires the most time, thereby preventing the achievement of high-speed processing.